User control for hearing prostheses

ABSTRACT

A hearing prosthesis whereby the change of a parameter by the user is only possible in discrete maximum steps, with the availability for further increments being dependant upon some conditional event or occurrence (“condition” herein) represented by one or more parameters such as the time which has elapsed since some previous event. In embodiments in which the parameter(s) include an event, such event may be, for example, the initial fitting or adjustment by a clinician, the last user adjustment, the last upward adjustment by the user, etc. In certain embodiments, the condition parameter(s) may include, for example, an elapsed period of time, a certain quantity of stimuli at a particular current level, or some combination of time, stimulation count and stimulation level. In alternative embodiments, there may be a tiered set of increasing increments, of which more gradually are available over time.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Australian Patent No.2005901007, filed on Mar. 3, 2005, and entitled, “User Control forHearing Prostheses,” the entire disclosure and contents of which arehereby incorporated by reference herein.

BACKGROUND

1. Field of the Invention

The present invention relates to hearing prostheses and, moreparticularly, to user control of a hearing prosthesis.

2. Related Art

Hearing prostheses, such as cochlear implants (also referred to ascochlear prostheses, cochlear devices, and the like; for simplicityhereinafter referred to as “cochlear implant”) and hearing aids, arewidely used to assist people with total or partial hearing loss. Ingeneral, modern devices of all types require the adjustment of operatingparameters by skilled persons at the time of fitting.

For example, in the case of cochlear implants, after implantation thereis a lengthy fitting process. The audiologist or clinician is requiredto create an initial map of electrodes, with various operatingparameters for each electrode. The map is used to create the specificstimuli which are applied to the electrode, in accordance with thespeech processing strategy employed by the particular implant system.

One of the more important operating parameters for each electrode is thedynamic range. This is generally set between two levels: the thresholdor T level, which is the minimum stimulus which evokes a percept ofsound, and the maximum comfortable or C level, which is the maximumstimulus which is not painful or damaging for the user (also referred toas the patient or recipient). It is desirable, for optimum perception ofsound and speech by the user, that the dynamic range be correctly set.If it is too small, the range of amplitudes which can be perceived bythe user is less than it could be, leading to a reduction in the rangeof different percepts which are possible and hence to reducedperformance in speech perception. If the T level is too low, thenstimuli are applied which cannot be perceived. If the C level is toohigh, then the patient may be overstimulated, leading to pain andpossible injury to the patient.

It is known in some systems, for example in the Nucleus 4 system, to usea neural response based telemetry system to set a basic profile for eachelectrode. This is typically optimized by the clinician.

However, it is known that over time, and especially over the first fewmonths of use, the dynamic range should be increased as the user becomesaccustomed to the implant. Further, users may wish to have some controlover the dynamic range of their implant.

Several approaches have been applied to address the issue of alteringthe dynamic range. For example, one approach is to use progressive maps,with increasing dynamic range, that are programmed into the speechprocessor. The patient may be encouraged, for example, to move to thenext map each month. This needs to be done with great care, as the usermay inadvertently choose the wrong map, and be overstimulated.

Another approach is to use the volume control of the map to allow theuser to change the dynamic range. This approach also carries a risk thatthe user will select too large a dynamic range, and consequently beover-stimulated.

Another approach suggested has been to allow users to change their ownprofiles of T and C levels using shift and tilt controls. Again, thiscarries a risk that the user will select too large a dynamic range, andconsequently be over-stimulated.

In the case of children, one of their parent(s) or caretaker(s) is/aregenerally the person/persons making such adjustments for the user. Inmany cases, they are cautious about altering settings, as they areconcerned that the levels may become too loud for the child recipient.Consequently, they are often reluctant to use the existing systems tovary dynamic range. (In this and subsequent discussions, the term“user,” “recipient,” and “patient” is intended to encompass parent orcaretaker in the case of children or other users having reducedcapacity.

Although the foregoing is discussed mainly in the context of dynamicrange, similar issues arise for other user adjustments. In some casesthe incorrect adjustments may not potentially compromise safety, butthey may produce sub-optimal treatment for the patient.

SUMMARY

The present invention is generally directed to providing a hearingprosthesis whereby the change of an operating parameter by the user isonly possible in discrete maximum steps, with the availability forfurther increments being dependant upon some conditional event oroccurrence (“condition” herein) represented by one or more conditionparameters such as the time which has elapsed since some previous event.In embodiments in which the condition parameter(s) include an event,such event may be, for example, the initial fitting or adjustment by aclinician, the last user adjustment, the last upward adjustment by theuser, etc. In certain embodiments, the condition parameter(s) mayinclude, for example, an elapsed period of time, a certain quantity ofstimuli at a particular current level, or some combination of time,stimulation count and stimulation level. In alternative embodiments,there may be a tiered set of increasing increments, of which moregradually are available over time.

BRIEF DESCRIPTION OF DRAWINGS

Implementations of the present invention will be described withreference to the accompanying figures, in which:

FIG. 1 is a functional schematic diagram of cochlear implant system inwhich embodiments of the present invention may be advantageouslyimplemented;

FIG. 2A is a flowchart showing the clock based control function of asoftware implementation of one embodiment of the present invention;

FIG. 2B is a flowchart showing control of user requests to increasedynamic range in accordance with one embodiment of the presentinvention; and

FIG. 3 is a graph showing constraints on C level adjustment which it maybe desirable to impose on a user, in accordance with one embodiment ofthe present invention.

DETAILED DESCRIPTION

Introduction to Selected Embodiments

The present invention is generally directed to providing a hearingprosthesis whereby the change of an operating parameter by the user isonly possible in discrete maximum steps, with the availability forfurther increments being dependant upon some conditional event oroccurrence (“condition” herein) represented by one or more conditionparameters such as the time which has elapsed since some previous event.In embodiments in which the condition parameter(s) include an event,such event may be, for example, the initial fitting or adjustment by aclinician, the last user adjustment, the last upward adjustment by theuser, etc. In certain embodiments, the condition parameter(s) mayinclude, for example, an elapsed period of time, a certain quantity ofstimuli at a particular current level, or some combination of time,stimulation count and stimulation level. In alternative embodiments,there may be a tiered set of increasing increments, of which moregradually are available over time.

According to one aspect, the present invention provides a hearingprosthesis including a processor and memory means, the prosthesis beingadapted to deliver stimuli to a user, said stimuli being determined bysoftware in response to a sound signal and at least in part by operatingparameters stored in said memory means, wherein said prosthesis furtherincludes a clock, and at least one of said operating parameters can beadjusted by the user, the adjustment being limited by reference to thetime or a function of the time as determined by said clock since apredefined event. The prosthesis may be a hearing aid, cochlear implantor other device.

According to another aspect, the present invention provides a method forcontrolling the adjustment of operating parameters in a hearingprosthesis, the prosthesis including a processor and memory means andbeing adapted to deliver stimuli to a user, said stimuli beingdetermined by software in response to a sound signal and at least inpart by parameters stored in said memory means, said method comprising:providing a clock; said user selecting a condition parameter to adjust;permitting adjustment of said parameter, the extent of adjustment beinglimited by reference to the time or a function of the time as determinedby said clock since a predefined event.

According to another aspect, the present invention provides a hearingprosthesis including a processor and memory means, the prosthesis beingadapted to deliver stimuli to a user, said stimuli being determined bysoftware in response to a sound signal and at least in part byoperational parameters stored in said memory means, wherein saidprosthesis further includes a clock, and wherein a process in saidprosthesis is triggered by reference to the time or a function of thetime as determined by said clock since a predefined event.

According to another aspect, the present invention provides a soundprocessor adapted to form part of a cochlear implant system, saidprocessor including a processor and memory means, said sound processorbeing adapted to process sound signals and produce stimulationinstructions for an implanted electrode array, said stimulationinstructions being determined by software in response to a sound signaland at least in part by parameters stored in said memory means, whereinsaid sound processor further includes a clock, and at least one of saidoperating parameters can be adjusted by the user, the adjustment beinglimited by reference to condition parameters such as the time or afunction of the time as determined by said clock since a predefinedevent.

According to another aspect, the present invention provides a computerprogram embodied on a computer readable medium for controlling theadjustment of operating parameters in a hearing prosthesis, theprosthesis including a processor and memory means, and being adapted todeliver stimuli to a user, said stimuli being determined by software inresponse to a sound signal and at least in part by parameters stored insaid memory means, wherein said prosthesis further includes a clock, andat least one of said parameters can be adjusted by the user, theadjustment being limited by reference to the time or a function of thetime as determined by said clock since a predefined event. Accordingly,the present invention allows for the use of an arrangement including aclock, so as to limit the extent of change permitting at a given time.

The term clock includes any means capable of measuring and/or indicatingthe passage of time, the number of instances one or more events haveoccurred, or some suitable combination of the two. Time may be,relevantly, the elapsed operating time of the prosthesis since someevent. The function of the clock is to allow for measurement of arelevant elapsed time period, and/or count of events, and not merely theprovision of regular timing pulses. Suitable clock devices may include,for example, a microprocessor clock having a crystal that vibrates at aregular frequency when an electrical current is applied to it, coupledwith suitable software and memory, or a logical counter capable ofrecording instances a stimuli is at a pre-determined level.

The degree of operating parameter control required will vary withdifferent users and for different parameters. Adjustment may bepermitted of only one or a few operating parameters, or of a broaderrange of operating parameters, for an experienced user. The varyingextent of user control permitted may be usefully controlled by theclinician during consultations.

The operating parameters which are suitable for adjustment will varywith the type of prosthesis and the way the particular device isconfigured. For example, for a cochlear implant, the operatingparameters could include dynamic range (either for all, some, orselected groups of electrodes), T and C levels separately (again, eitherfor all, some, or selected groups of electrodes), stimulation rate,pulse width or any other desired parameter. The adjustment could operateon a per-channel or group of channels basis, but where appropriate(e.g., dynamic range) it could permit changes across all channels.

Description of Exemplary Embodiments

The present invention will be further described with reference to aparticular implementation suitable for a specific cochlear implantsystem. It will be understood that the present invention may be appliedto other hearing prostheses now or later developed such as hearing aidsor brain stem implants, or to other cochlear implant systems withmodifications as required in those environments.

Further, the following discussion concentrates on adjustment of C levelsin an electrode map. If other operating parameters are to be varied, itwill be understood to apply the teachings of the present invention tosuch other operating parameters, and that the particular risks andtherapeutic requirements for such operating parameters will need to betaken into account in setting the appropriate constraints andpermissions.

Referring now to FIG. 1, an illustrative example of an implementation ofthe present invention is shown. Speech processor 10 includes amicroprocessor 11 in communication with memory 12, clock 13, and DSP 15.Input sound signals from microphone 20 are received by AD converter 14and passed to DSP 15. Under the control of microprocessor 11, DSP 15processes the digitized sound signals, and outputs stimuli for use bythe electrode array 30 and/or speaker 18.

It will be understood that there is considerable complexity in thespeech processing software and in the selection of appropriate stimulifor delivery. The present invention is concerned with these aspects inas far as it concerns the adjustment of particular operating parameters,and accordingly, these aspects will not be described in further detailherein. Such systems are commercially available and understood by thoseof ordinary skill in the art. Similarly, the physical arrangements ofthe system will not be dealt with in detail. Parts of the presentimplementation may be physically placed in the implanted device, in thespeech processor or even in a separate device which provides the userinterface (for example in the form of a small remote control). Thepresent invention may also be implemented in a totally implanted systemfor example as described in WO 2002/05590 in the in the name of CochlearLimited, incorporated herein by reference. These are matters ofimplementation detail which depend upon the respective system.

In the system shown in FIG. 1, memory 12 stores an electrode map for theuser. This map includes details and operating parameters for eachelectrode, including T and C values. Stimuli to be delivered via therespective electrode are selected so that their amplitude falls withinthe dynamic range defined by the T and C values. An example of a mappingprocedure is described in WO2004/004412 in the name of Cochlear Limited,hereby incorporated by reference herein.

User interface 40 is shown as a separate element, and may convenientlybe in the form of a small remote control device as is conventionallyused for control of digital hearing aids. Any alternative interface,such as controls on the speech processor or even user software on apersonal computer (PC) or similar device may be used.

If the user determines that he would prefer to increase the C level, heinputs this request via the user interface 40. For the purposes of thisexample, we will assume that this is intended to increase the C levelproportionately across all channels, although it will be appreciatedthat more specific requests per channel, channel groups, etc. could betreated similarly.

For example, the software may allow for a certain constrained increaseonce the user has been stimulated at the current maximum C level for10,000 times across all channels since the last clinician visit. It mayallow no increase until that level is increased. Alternatively, it mayallow a proportionate increase based on the number of stimulations atthat level. The increases may be permitted to set levels, preferably asan increment of the previous level, after certain numbers ofstimulations at the current C level.

A more complex conditional function could also be used, based aroundtime but taking into account numbers of stimulations as well.Alternatively, a purely time elapsed system could be used.

In one embodiment, the increase permitted is proportion of the current Clevels, so that any increase must be moderate. Absolute limits couldalso be provided for the C level increases, even over time.

Account could also be taken of the time since the last increase.

FIG. 2A illustrates one way a clock-based control function could operatein the context of the present example. It will be understood that theparticular operating parameter selected, C level, is arbitrary and thesame or similar operations may be implemented to adjust any suitableoperating parameter.

In the process 200 illustrated in FIG. 2A, after start block 202, a timevalue condition parameter is set at block 204 to a value of zero (t=0),and a time value condition parameter is set at block 206 to a value ofzero (count=0). In subsequent operations, process 200 waits for a period(here, 1 ms) at block 208, then determines at block 210 if the user hasbeen stimulated at the C level. If so, then the count value isincremented by one at block 212. If not, then after another wait atblock 208, the operation at block 210 is repeated. The incrementing ofthe count value at block 212 maintains the count of how often the userhas been stimulated at the C level. The process then tests if the countexceeds, in this example, the 10,000 count level. If so, the time isincremented, and the above process is repeated as shown in FIG. 2A. Ifthe count is not at 10,000, then counting process continues to repeat.

FIG. 2B is a flowchart of a process 250 illustrating one embodiment ofthe operations which may be performed in response to a user's request toadjust the dynamic range of the hearing prosthesis. At block 250 a userrequests an increase of the dynamic range (it should be appreciated thatthe dynamic range is also considered to be an operating parameter,albeit one defined by two other operating parameters, V, T and Clevels.). The required T and C levels are calculated at block 254. Byreferring to criteria, for example the count and time conditionparameters of FIG. 2A, or the values of any other condition parametersrepresentative of the selected condition, process 250 determines atblock 256 if increase as requested is allowed, and modifies the levelsat block 258 if permitted. Process 250 then ceases at block 260.

FIG. 3 illustrates graphically how user control limitations correspondto the expected permitted increase over time. The time axis is in unitsof months. It is expected that the C level 302 should increase, and theT level 304 decrease over time after implantation, so that the dynamicrange increases. The parameters setting permission to increase thedynamic range may be dependent on a conservative estimate of expectedchanges to the C and T levels. As the number of stimulations at the Clevel over time increases, the permitted increase cumulatively rises.

It will be understood that this process may be applied to otherparameters in a similar manner. The provision of a clock as a cumulativemeasure allows the use of sophisticated gradual control by the user. Itis also noted that the clock function may be implemented in variousways, in combination with other components and functions, and should notbe understood as limited to the particular implementation described.

The process may also be used in association with other measures. Forexample, the clock and stimulation count may be used to trigger eitheran automatic or user-driven automatic recalibration of C and T levels,using the systems already provided for this purpose in some commerciallyavailable systems. Alternatively, after certain time/stimulation countsthe user could be prompted to subjectively set C and T levels based uponsignals generated by a test mode of the speech processor. It will beappreciated that a wide variety of measures can be potentiallycontrolled in this way, and the parameters should be understood toinclude matters extending beyond strictly the operating parameters ofthe cochlear implant, or other auditory prosthesis.

All documents, patents, journal articles and other materials cited inthe present application are hereby incorporated by reference.

Although the present invention has been fully described in conjunctionwith several embodiments thereof with reference to the accompanyingdrawings, it is to be understood that various changes and modificationsmay be apparent to those skilled in the art. For example, in the aboveembodiments the operations performed to limit the adjustment incrementsof the operating parameters are performed in software executing on aprocessor or microprocessor. It should be understood, however, that inalternative embodiments of the present invention may be implemented incomputer hardware such as in an ASIC, or other hardware now or laterdeveloped. It should also be appreciated that the parameters that areconsidered by embodiments of the present invention, when determining theincrement of the adjustment limits of the operating parameters; that is,the condition parameters may include operating parameters. In otherwords, for some parameters, it is the use of the parameter which willdictate whether or not it is considered to be a conditioned parameter,an operating parameter, or both. Such changes and modifications are tobe understood as included within the scope of the present invention asdefined by the appended claims, unless they depart therefrom.

1. A hearing prosthesis adapted to deliver stimuli to a user comprising:memory means; a clock; and a processor configured to determine saidstimuli in response to a sound signal and at least in part by usingparameters stored in said memory means, allow said parameters to beadjusted by the user, and limit the adjustment by the user of saidparameters by reference to an amount of time, as determined by saidclock, or a function based around an amount of time since a predefinedevent.
 2. The prosthesis of claim 1, wherein said function based aroundan amount of time comprises: one or more of said time elapsed since saidevent, a quantity of times at least one of said parameters has beenutilized since said event, and a cumulative use of at least one of saidparameters since said event.
 3. The prosthesis of claim 2, wherein saidevent comprises one or more of the group comprising: a fitting of theprosthesis; a last adjustment of the prosthesis by a clinician; and alast adjustment of said at least one of said parameters or another oneof said parameters.
 4. The prosthesis of claim 1, wherein the prosthesisis a cochlear implant further comprising: an implanted stimulator; and aspeech processor, wherein said processor, memory means and clock arelocated in said speech processor.
 5. The prosthesis of claim 1, whereinthe prosthesis is a hearing aid, and the stimuli delivered are acousticstimuli.
 6. The prosthesis of claim 1, wherein the parameters areseparately adjustable for each channel or group of channels.
 7. Thehearing prosthesis of claim 1, wherein the parameters that can beadjusted by the user comprise at least one of a C-level and/or aT-level.
 8. The hearing prosthesis of claim 1, wherein the parametersthat can be adjusted by the user comprise at least one of a stimulationrate and/or a pulse width.
 9. A hearing prosthesis adapted to deliverstimuli to a user, the hearing prosthesis comprising: a processor; amemory means; and a clock; wherein the processor is configured todetermine said stimuli in response to a sound signal and at least inpart by using parameters stored in said memory means, and wherein theprocessor is configured to trigger, by reference to an amount of time,as determined by said clock, or a function based around an amount oftime since a predefined event, the execution of a process to recalibrateone or more of said parameters.
 10. The hearing prosthesis of claim 9,wherein the process includes a prompt to the user.
 11. The hearingprosthesis according to claim 9, wherein the process includes automaticchanges to parameters or tests to refine parameters.
 12. The hearingprosthesis of claim 9, wherein said event comprises one or more of thegroup comprising: a fitting of the prosthesis; a last adjustment of theprosthesis by a clinician; and a last adjustment of one of saidparameters.
 13. The hearing prosthesis of claim 9, wherein theprosthesis is a cochlear implant further comprising: an implantedstimulator; and a speech processor, wherein said processor, memory meansand clock are located in said speech processor.
 14. The hearingprosthesis of claim 9, wherein the hearing prosthesis is a hearing aid,and the stimuli delivered are acoustic stimuli.
 15. The hearingprosthesis claim 9, wherein the process, when executed, causes theprocessor to adjust at least one of said parameters.
 16. The hearingprosthesis of claim 15, wherein the at least one adjusted parameter isseparately adjustable for each channel or group of channels of theprosthesis.
 17. The hearing prosthesis of claim 15, wherein the at leastone adjusted parameter comprises a plurality of adjusted parameters. 18.The hearing prosthesis of claim 15, wherein the at least one adjustedparameter comprises at least one of a C-level and/or a T-level.
 19. Thehearing prosthesis of claim 15, wherein the at least one adjustedparameter comprises at least one of a stimulation rate and/or a pulsewidth.
 20. A computer-readable medium encoded with a computer programfor controlling the adjustment of operating parameters in a hearingprosthesis, the prosthesis including a processor, a clock and memorymeans, and being adapted to deliver stimuli to a user, wherein thecomputer program when executed by the processor causes the prosthesis todetermine said stimuli in response to a sound signal and at least inpart by using parameters stored in said memory means, enable at leastone of said parameters to be adjusted by the user, and limit theadjustment by the user of said parameters by reference to an amount oftime, as determined by said clock, or a function based around an amountof time since a predefined event.